Manufacture of flexible tubes



June 23, '1936. R, DEBENEDETTl v 2,045,540

MANUFACTURE OF FLEXIBLE TUBES- y Filed May l1, 1953 Patented June' 2.3, 1936 Application Y This invention relates tothe manufacture of exible metal tubes of the kind having an outer rubber coating and including a protecting continuouslayer intermediate the continuous metal body of said tube and said rubber coating, such sting of a derivative of cellulose, of the kind disclosed in my copending application illed February 25, 1931, Ser. No. 518,20

As known, said composite flexi are particularly useful in handling and conveying iiuids, as `gasoline and the like, capable of 'affecting rubber and equivalent materials.

It is known that flexible lms may be obtained from derivatives of cellulose, such as regenerated cellulose which is particularly useful to provide said protecting layer, but such lms have an inextensible character.. i

Therefore, when materials of the above class are used to provide a protecting layer intended to prevent any uid which could leak through the coils of the metal tube body from reaching and attacking the outer rubber coating(in tubes of the above defined class. said layer must be pros videdv with transverse corrugations to allow elongation when the composite tube is bent.

In the embodimentvdisclosed in my copending application hereinbefore referredv to, said corrugations are obtained by means of a cord` which is coiled and tightened over said layer located on the metal body of the tube, to cause it to enter the helicoidal groove existing between'adjacent coils providing saifdmetal body of the tube.

The present invention has for its object an im-. proved method forl producing in the protecting layer located intermediate thafrpetal body of the tube and its outer rubber coatingla helicoidal ufcientdepth for the purpose the sheetprovidiiis-klv said layer being required to move 4or slide over or alongsaid metal body during the formation of said groove.

The method of this invention is hereinafter dereference tofthe annexed drawing ble metal l tubes groove having a s intended, without scribed with where the steps of the operation are illustrated f a central fragmentary section of a length of a blank of tube preparatory to location of the protecting layer-thereon;

Figure 2 -is a section similar to' subsequent to the location of protective layer over,- the tube metal body;

Figure 3 is a fragmentary sect tube having an outer rubber coating afdxed theretory to the step of vulcanizing the Fig. 1 m the' step ion of av length of "UNITED STATES PATENT oFFicE MANUFACTURE oF FLEmLE TUBES noaouo Debenedetti, Turin, Italy, signor to gicago Tubing a Braiding Company, Chicago,

11, 1923, serial No. 670,589 mlynay 25,1932

Figure 4 is a section similar to Figure 3 of the completed tube.

In carrying out the method of this invention, an internal metal body is prepared in usual manner by wrapping helicoidally a reverse channel 5 metal strip I to provide adjacent coils having interengaged edges as I' and I''; said channel metal strip has conveniently a rounded cross section in its outwardly extending portion as illustrated at I". l,

To provide the impervious protecting layer above referred to, one or more bandsl 4 consisting of a film of cellulosic material are wound or wrapped over body I, while this body I is held stretched or elongated in the condition shown in Figure 1, that is having the side' flanges or edges I', I" of subsequent coils in contact with each other.

Said bands 4 then provide a cylindricaltube which bears on said body I only in register with the most prominent portions I- of each coil of said'body I. l

'I'he body I is then causedtocontract or collapse longitudinally or endwise in any suitable manner, say by locating it on a core or mandrel not shown and. by causing its ends to approach each other, the adjacent coils being thus caused I-to again take up their normal position and overlapv as shown in Figure 2.

Due to such endwise collapse of metal body I, l

said layer 4 of cellulose derivative is caused to 3o fold and pleat in the region 4'-of the sameincluded between the lines of its contact with prominent portions I" of body I, as shown inA Figure 2. Saidpleating of sheath 4 occurs due to the fact that such sheathvis soft in v iew both of the material it is made'of'. and of its small thickness and also due to the fact that owing tolits support onienlarged'fportional" of themetaltube I said Isheath adheres to this tube in register with such portions I". v 4o Therefore said sheath while being smooth and even at the time the metal reinforcement tube I is stretched, collapses and provides pleats whenI saidtube is allowed to collapse.

Of`l course, as described in my said copending -45- applicationa cord (not shown) may be wound over layer 4 in the region of pleats 4` to cause such pleats to enter the helicoidal groove 6 between coilsof body I. I The tube is then completed by/afrxing a coating 3 oi' uncured or not vulcanized rubber which is then enclosed within an outerl envelope 1, and finally the composite structure is heated to cure and vulcanize said rubber coating 3. s

Due to such treatment, the rubber of coating caused to enter the same (Figure 4).

The tube thus completed is finally released from envelope 1.

In the completed tube, as shown in Figure 4,

the layer 4 is thus provided with a continuous helicoidally grooved or depressed portion f4 whichV is supported from outside by a comparatively soft internal ridge 3l of rubber coating 3, the

corrugated portions of said layer being thus en- `abled to follow the bending or exure of the of the tube.

`tube withoutbeing subject to a harmful stretching.

Ihe particular contour of channel metal strip availed of to provide body I has the advantage that layer 4 never may contact with sharp edges of such metal body and therefore it cannot be torn off during the manufacture of the tube nor due to movements the protecting layer 4 may eiect with respect to the internal metal body or core What I claim as my invention and desire to secure by United States Letters Patent is:-

1. A method for manufacturing exible metal tubes having a core consisting of a coiled sheet metal strip, an impervious layer on said core and an outer coating 'of a material of the class of rubber, comprising stretching said core longitudinally, locating said layer thereon, collapsing said core longitudinally to cause said layer to pleat in register at the region of overlap of said metal strip forming said core, and then afxing said coating over said layer.

2. A method for manufacturing flexible metal tubes having a core of a coiled channel sheet metal strip, an impervious layer on said core and an outer coating of a material of the class of rubber, comprising stretching said^core longitudinal- 1y, locatingsaid layer thereon, collapsing said core longitudinally to produce a groove therein in register with the interengaged adjacent portions of said channel metal strip and to cause said'layer to pleat in register with such groove, and then afilxing said coating on said layer.

3. A method for manufacturing flexible metal tubes having a core of a coiled reverse channel ,shaped sheet metal strip, an impervious layer on said core and an outer coating of a material of the class of rubber, comprising stretching said core longitudinally, locating said layer thereon, collapsing said core longitudinally to produce a groove therein in register with the interengaged adjacent portions of said channel metal strip and to cause said layer to pleat in register with such groove, and then amxing said coating on said layer.

4. A method for manufacturing exible metal tubes having a coreof a coiled sheet metal strip. an impervious layer on said core and an outer coating of a material of the class of rubber, comprising stretching said core longitudinally, locatingsaid layer thereon, collapsing said core longitudinally'to cause said layer to pleat in register .in the region of overlapof said metal strip l forming said, core,.aflixing said rubber material tubes having a core of a coiled channel sheet metal strip, an impervious layer on said core and an outer coating of a material of the class of rubber, comprising stretching said core longitudinally, locating said layer thereon, collapsing said core longitudinally to produce a groove therein in register with the interengaged adjacent portions of, said channelmetal strip and to cause said layer to pleat lin register with such groove, afxing said rubber-material coating in an unvulcanized state over said layer, enclosing the whole in an envelope and vulcanizing said coating therein, the portions of said coatingl register with said groove which swell out due tcsaid vulcanization forcing said layer pleats into said groove and yieldably backing them.

6. A method for manufacturing exible metal tubes having a core of a coiled reverse channel shaped sheet metal strip, an impervious layer on said core and an outer coating of a material of the class of rubber, comprising stretching said core longitudinally, locating said layer thereon, collapsing said core longitudinally to produce a groove therein in register with the interengaged adjacent portions of said channel metal strip and to cause said layer to pleat in register with such groove, amxing said rubber-material coating in an unvulca'nized state over said layer, enclosing the whole in an envelope and vulcanizing said coating therein, the portions of said coating in register with said groove which swell out due to said vulcanization` forcing said layer pleats into said groove and yieldablylbacking them.

7. A method for manufacturing exible metal tubes having a coiled sheet metal strip core, an impervious layer on said core and an outer coating of the class of the rubber, comprising coiling helicoidally a reverse channel shaped metal strip comprising a flat channel portion opening outwardly and arounded channel portion opening inwardly and providing a rounded ridge on the outside of said core, stretching said core longitudinally, locating said layer thereon, collapsing said core longitudinally to produce a groove therein in register with said interengaged adjacent channel portions and to cause said layer to pleat in register with said groove, aflixing said rubber-material coating in an unvulcanized state over said layer,enclosing the whole in an envelope and vulcanizing said coating therein, the portions of said coating in register witlr said groove me'tal strip helicoidally so as to form an extensible core, then stretching said core longitudinally,

then applying an impervious layer upon said core when in stretched condition and then collapsing said core so as to form corrugations in said impervious la'yer.

l0. A method of manufacturing a flexible metal l tube comprising forming an extensible metal core, then extending said core longitudinally, then applying to saidrcore an impervious non-extensible which swell out due to said vulcanization forcing layer of material and then collapsing said core so 75 as to form pleats in said Aimpervious non-extensible layer. g

11. A method of manufacturing a flexible metal tube comprising forming an extensible metal core, then extending said core -longitudinally, then applying to said core an impervious non-extensible layer of material, then collapsig said core so as to form pleats in said impervious 1 'non-extensiblevlayer and then vulcaniz'ing about' said impervious non-extensible layer a rubber coating. v

12. A method of manufacturing a flexible metal tube having a flexible core and an impervious layer on said core including the steps of stretching said core longitudinally, then placing said vimpervious layer thereon, then collapsing said core longitudinally to produce corrugations in said impervious layer and then forcing said corrugations into a groove upon said exiblecore.- A 

